What Is Osteoarthritis? continued...

With osteoarthritis, the cartilage gradually breaks down. Cartilage is a slippery material that covers the ends of bones and serves as the body's shock absorber. As more damage occurs, the cartilage starts to wear away, or it doesn't work as well as it once did to cushion the joint. As an example, the extra stress on knees from being overweight can cause damage to knee cartilage. That, in turn, causes the cartilage to wear out faster than normal.

As the cartilage becomes worn, cushioning effect of the joint is lost. The result is pain when the joint is moved. Along with the pain, sometimes you may hear a grating sound when the roughened cartilage on the surface of the bones rubs together. Painful spurs or bumps may appear on the end of the bones, especially on the fingers and feet. While not a major symptom of osteoarthritis, inflammation may occur in the joint lining as a response to the breakdown of cartilage.

Osteoarthritis is very common and can coexist with other types of arthritis such as rheumatoid or gout.

What Is Rheumatoid Arthritis?

Rheumatoid arthritis is the most common type of inflammatory arthritis. More than 1.3 million Americans are affected. According to the American College of Rheumatology, about 75% of those affected are women. In fact, between 1% and 3% of women are likely to develop rheumatoid arthritis in their lifetime.

Rheumatoid arthritis is an autoimmune disease. That means that the immune system attacks parts of the body. For reasons that aren't clear, the joints are the main areas affected by this malfunction in the immune system. Over time, chronic inflammation can lead to severe joint damage and deformities. About one out of every five people who have rheumatoid arthritis develop lumps on their skin called rheumatoid nodules. These often develop over joint areas that receive pressure, such as over knuckles, elbows, or heels.